Ball bats with lightening perforations

ABSTRACT

A ball bat includes a barrel wall with perforations positioned within a ball striking area of the bat. Perforations may extend through all or part of the barrel wall. In some embodiments, a filler material may be positioned in the perforations, or a cover element may be positioned over the perforations, to form a generally flush surface between the filler material and a surface of the barrel wall. Filler material may be less dense than material forming the remainder of the barrel wall. In some embodiments, a barrel wall may include a plurality of layers of composite laminate material. One or more of the layers may have perforations positioned radially between the other layers. In some embodiments, the perforations in the composite laminate material may be generally aligned to form a larger perforation extending through all or part of the barrel wall.

BACKGROUND

Ball bats, such as bats for baseball or softball, may be made with metal materials, composite materials, or combinations of materials. Ball bats that include metal materials may include aluminum, magnesium, or alloys of various metals. Composite ball bat components are often made with one or more layers or plies of composite laminate material that may be arranged concentrically around the bat's longitudinal axis, which is often referred to as the bat's X-axis. For directional reference, the bat's Z-axis is oriented perpendicular to the X-axis and through the bat wall.

Sports governing bodies have implemented restrictions on bat performance, including a restriction on the Bat-Ball Coefficient of Restitution (“BBCOR”). Some governing bodies have established limits on the maximum BBCOR that a bat is allowed to exhibit when the bat is new and when it is broken-in through normal wear or abuse. Some governing bodies require that a bat meet requirements after an accelerated break-in (“ABI”) process, such as after “rolling” a bat or otherwise compressing it, or after generating hard hits to the bat with an object other than a ball.

Implementation of restrictions on BBCOR and other performance measures has resulted in many manufacturers making bat barrels stiffer by increasing their wall thickness, which generally yields heavier bats and increases their swing weight, thereby increasing the difficulty of swinging the bat. Increased swing weight is particularly problematic for players who desire the lightest swing weight possible, such as many youth batters. Performance restrictions have also resulted in bats being made with increased durability far beyond what is practically necessary for normal use in play.

SUMMARY

Representative embodiments of the present technology include a ball bat having a barrel wall with a plurality of perforations positioned within a ball striking area. Perforations may extend through all or part of the barrel wall. In some embodiments, a filler material may be positioned in one or more of the perforations (such as all of the perforations), or a cover element may be positioned over one or more of the perforations (such as all of the perforations), to form a generally flush surface between the filler material and an outer surface of the barrel wall. The filler material may be a different material than the surrounding barrel wall material and may have a density or specific gravity value less than a density or specific gravity value of material forming the remainder of the barrel wall. In some embodiments, a barrel wall may include a plurality of layers of composite laminate material. One or more of the layers may have perforations positioned radially between other layers. In some embodiments, the perforations in the composite laminate material may be generally aligned to form a larger perforation extending through all or part of the barrel wall.

Embodiments of the present technology provide ball bats with lighter weight, such as lighter swing weight, while maintaining compliance with performance regulations.

Other features and advantages will appear hereinafter. The features described above can be used separately or together, or in various combinations of one or more of them.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein the same reference number indicates the same element throughout the several views:

FIG. 1A illustrates a ball bat having a barrel portion and a handle portion, in accordance with embodiments of the present technology.

FIG. 1B illustrates a cross-sectional view of the bat shown in FIG. 1A, in accordance with embodiments of the present technology.

FIGS. 2A and 2B illustrate isometric and side views, respectively, of a portion of a ball bat in accordance with embodiments of the present technology.

FIG. 2C illustrates a cross-sectional view of a ball striking area of a portion of a ball bat shown in FIGS. 2A and 2B, with the addition of a cover element, in accordance with embodiments of the present technology.

FIG. 2D is a chart of filler materials that may be used in embodiments of the present technology, their specific gravity values, and their approximate weight savings relative to 6061 Aluminum.

FIG. 3A illustrates a cross-sectional view of a stack of composite laminate layers with perforations, the stack forming at least part of a barrel wall, according to embodiments of the present technology.

FIG. 3B illustrates a face-on cross-sectional view of a section of a ball bat, such as at least a portion of the section represented in FIG. 3A.

FIG. 4A illustrates a cross-sectional view of a stack of composite laminate layers with perforations, the stack forming at least part of a barrel wall, according to further embodiments of the present technology.

FIG. 4B illustrates a face-on cross-sectional view of a section of a ball bat, such as at least a portion of the section represented in FIG. 4A.

DETAILED DESCRIPTION

The present technology is directed to ball bats with lightening perforations, and associated systems and methods. Various embodiments of the technology will now be described. The following description provides specific details for a thorough understanding and enabling description of these embodiments. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, conventional or well-known aspects of ball bats, metals, and composite materials may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments. Accordingly, embodiments of the present technology may include additional elements, or may exclude some of the elements described below with reference to FIGS. 1A-4B, which illustrate examples of the technology.

The terminology used in this description is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this detailed description section.

Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of items in the list. Further, unless otherwise specified, terms such as “attached” or “connected” are intended to include integral connections, as well as connections between physically separate components.

FIG. 1A illustrates a ball bat 100 having a barrel portion 110 and a handle portion 120. There may be a transitional or taper portion 130 in which a larger diameter of the barrel portion 110 transitions to a narrower diameter of the handle portion 120. The handle portion 120 may include an end knob 140, and the barrel portion 110 may optionally be closed with an end cap 150. The barrel portion 110 may include a non-tapered or straight section 160 extending between the end cap 150 and an end location 170. In various embodiments, the taper portion 130 may include some of the barrel portion 110, or some of the handle portion 120, or both.

The bat 100 may have any suitable dimensions. For example, the bat 100 may have an overall length of 20 to 40 inches, or 26 to 34 inches. The overall barrel diameter may be 2.0 to 3.0 inches, or 2.25 to 2.75 inches. Typical ball bats have diameters of 2.25, 2.625, or 2.75 inches. Bats having various combinations of these overall lengths and barrel diameters, or any other suitable dimensions, are contemplated herein. The specific preferred combination of bat dimensions is generally dictated by the user of the bat 100, and may vary greatly among users.

The bat 100 may be constructed with any suitable material or combination of materials, and the bat 100 may be formed as a single integral piece or it may be formed with multiple pieces joined together. For example, the barrel portion 110 may be constructed with one or more metal or composite materials. Some examples of suitable composite materials include laminate plies reinforced with fibers of carbon, glass, graphite, boron, aramid (such as Kevlar®), ceramic, or silica (such as Astroquartz®). Some examples of suitable metal materials include aluminum, magnesium, or other metal materials or combinations of metal materials or alloys. The handle portion 120 may be constructed from the same materials as, or different materials than, the barrel portion 110.

The ball striking area of the bat 100 typically extends throughout the length of the barrel portion 110, and may extend partially into the taper portion 130 of the bat 100. The barrel portion 110 generally includes a “sweet spot,” which is the impact location where the transfer of energy from the bat 100 to a ball is generally maximal, while the transfer of energy (such as shock or vibration) to a player's hands is generally minimal. The sweet spot is typically located near the bat's center of percussion (COP), which may be determined by the ASTM F2398-11 Standard. Another way to define the location of the sweet spot is between the first node of the first bending mode and the second node of the second bending mode. This location, which is typically about four to eight inches from the distal free end of the bat 100 (the end with the optional cap 150), generally does not move when the bat is vibrating. For ease of measurement and description, the “sweet spot” described herein coincides with the bat's COP.

For purposes of orientation and context for the description herein, FIG. 1 also illustrates a bat coordinate system 180 having axes X, Z. The X-axis corresponds with the longitudinal axis of the bat 100, spanning along the length of the bat between the proximal end 190 and the distal (free) end 195. The Z-axis is oriented generally along a radial direction extending from the X-axis, transverse to the bat wall. For ease of description herein, the Z-axis will be used to refer to the radial direction passing through the thickness of a wall of the bat 100.

FIG. 1B illustrates a cross-sectional view of the bat 100 shown in FIG. 1A. In some embodiments of the present technology, the ball bat may include a barrel wall 196 surrounding a hollow interior cavity 197. In some embodiments, the interior cavity 197 need not be hollow throughout the entirety of the bat 100. For example, a bat 100 according to embodiments of the present technology may optionally include various supports or fillers in the interior cavity 197.

FIG. 2A illustrates an isometric view of a portion of a ball bat 200 with lightening perforations 210 in accordance with embodiments of the present technology. FIG. 2B illustrates a side-perspective view of the portion of the ball bat shown in FIG. 2A. For simplicity, an end knob (140) and end cap (150) are not shown in FIGS. 2A and 2B, although they may be included. The portion of the ball bat 200 illustrated in FIGS. 2A and 2B may be formed with metal materials, composite materials, or combinations of metal and composite materials.

In some embodiments of the present technology, the barrel wall 196 may include one or more holes or lightening perforations 210. For simplicity in illustration, only some such perforations 210 are labeled in FIGS. 2A and 2B. The perforations 210 may be distributed around the ball striking area of the bat 200. For example, the perforations 210 may be distributed along all or part of the barrel portion 110. In some embodiments, some perforations 210 may be positioned in the taper portion 130, although in some embodiments, perforations 210 may be positioned only in the straight section 160 (see FIGS. 1A, 1B), and not in the taper portion 130. The perforations 210 may be distributed circumferentially around the bat 200 in an even pattern or an uneven pattern, or in one or more combinations of patterns. For example, the perforations 210 may be positioned around the bat 200 in offset rows, as illustrated in FIGS. 2A and 2B. In some embodiments, offset rows may include rings of perforations 210 distributed around the circumference of the barrel wall 196 that are rotated relative to each other about the X-axis (as generally illustrated in FIGS. 2A and 2B). One or more (such as all) of the perforations 210 may extend through the entire barrel wall 196 (along the Z-axis). In some embodiments, one or more (such as all) perforations may extend only partially through the thickness of the barrel wall 196 (along the Z-axis; the thickness T1 is shown in FIG. 2C). For example, in some embodiments, perforations may be made from the outside toward the inside. In some embodiments, they may be made from the inside toward the outside.

In some embodiments, one or more of the perforations 210 may have circular cross-sections, or they may have other shapes formed by removal or omission of material. In some embodiments, the perforations 210 may have a width or diameter D between 0.040 inches and 0.125 inches. In other embodiments, one or more of the perforations 210 may have a width or diameter greater than 0.125 inches. The perforations 210 may be formed by drilling or otherwise cutting into the metal or composite material forming the structure of the bat 200.

Compared to bats without perforations, the perforations 210 reduce the bat's overall weight, and therefore the swing weight, while maintaining compliance with performance restrictions, such as BBCOR. For example, one or more ounces of material may be removed without increasing BBCOR or other performance measurements, or at least without unduly increasing BBCOR or other performance measurements beyond regulated limits. The inventors were surprised to discover that perforations 210 could be made in bat walls (including metal alloy or composite walls) to reduce bat weight without materially changing the BBCOR characteristic of the bats. Bats according to some embodiments of the present technology may have net weight savings of thirteen percent or more, or other weight savings.

In some embodiments, the perforations 210 may extend throughout the striking area along the X-axis. In some embodiments, however, perforations 210 may be positioned only in part of the striking area (as explained in additional detail above). In some embodiments, perforations 210 may be positioned in the striking area but at a distance away from areas of the bat that may see the most impacts during play, such as the sweet spot. In some embodiments, the perforations 210 may have the most effect on swing weight when they are closer to the free or distal end 195 of the ball bat (closer to the end cap 150) than to the proximal end 190 (closer to the handle portion 120 or end knob). Accordingly, in some embodiments, the perforations 210 may be positioned only between the “sweet spot” and the end cap 150, or otherwise generally toward the distal (free) end 195 of the ball bat. Positioning the perforations 210 such that they are concentrated toward the distal (free) end 195 of the ball bat provides more (for example, maximum) reduction in the moment of inertia (swing weight) of the bat. In some embodiments, however, if a relatively heavier swinging bat (a bat with relatively greater moment of inertia) is desired, the perforations 210 may be positioned closer to the batter's hands, such as closer to the sweet spot, or closer to the taper portion 130.

FIG. 2C illustrates a cross-sectional view of a ball striking area of a portion of a ball bat shown in FIGS. 2A and 2B, with the addition of a cover element 230, in accordance with embodiments of the present technology. Some sports governing bodies require that ball bats have a smooth or uniform outer surface. For example, some governing bodies require a ball bat to have a smooth surface forming a constant radius about any one point along the longitudinal axis (X-axis) of the bat. To comply with such requirements, in some embodiments, as generally illustrated in FIG. 2C, the perforations 210 may be filled with filler material 220, sealed with filler material 220 (even if the perforations are not entirely filled with the material), covered with a cover element 230, or otherwise suitably filled, sealed, or covered to create a generally smooth outer surface or flush surface between the filler material and the surrounding surface of the barrel wall. For simplicity in illustration, only one perforation 210 is shown as having filler material 220. However, in embodiments of the present technology, one or more perforations 210 (such as all the perforations 210) may include filler material 220.

In some embodiments, filler material 220 that may be positioned in the perforations 210 may include epoxy, composite material, thermoplastic polyurethane, polycarbonate, nylon, acrylonitrile butadiene styrene (ABS), resins such as SURLYN®, polyethylene (high density, low density, or otherwise), plastic material, polypropylene, natural rubber, foam of suitable densities, or combinations of materials. To reduce overall weight and maintain weight savings gained from the perforations 210, the filler material 220 should have a lower density than the material it is replacing (the material that was removed from the bat to form the perforations 210). In some embodiments, the filler material should be sufficiently strong to remain in the perforations 210 despite normal use and even abuse.

In some embodiments, some materials may reduce overall weight more than other materials, depending on the density of the selected material. For example, if a perforation 210 is made in a 6061 aluminum alloy bat, a low-density foam material (such as a foam material having a density of 6 pounds per cubic foot) may be used as filler material 220 to fill the perforation 210 for a weight savings of approximately 97% in the perforation 210. If a nylon material is used to fill the perforation, there may be a weight savings of approximately 58% in the perforation 210. A designer may customize the weight savings depending on the density of material 220 selected to fill the perforation 210. FIG. 2D provides other examples in a chart 240. The chart 240 in FIG. 2D provides the specific gravity value 250 (relative to water) of several materials that may be used as filler material 220 in embodiments of the present technology that have a 6061 aluminum alloy barrel wall (which is just one example of a suitable alloy that may form the barrel wall). Column 260 of the chart 240 lists the percentage weight savings that may result from replacing the 6061 aluminum material (removed from a barrel wall by forming the perforation) with filler materials 220 in a perforation 210, such as high density polyethylene (HDPE), natural rubber, or other materials listed in the chart 240.

In some embodiments, the cover element 230 that covers one or more (such as all) of the perforations 210 can be formed with a thin layer or shell of material, such as metal or composite material, or other materials suitable for use as a surface of a ball striking area in a ball bat. In some embodiments, the cover element 230 may have a thickness between 0.003 inches and 0.125 inches, such as approximately 0.020 inches. A thinner cover element may increase weight savings, but a thicker cover element may improve longevity and durability of the cover element, depending on the material forming the cover element 230. In some embodiments, the thickness and density of the cover element 230 may contribute to overall weight savings, and, in some embodiments, the thickness and density of the cover element may be selected to add less weight to the ball bat 200 than the weight removed by creating the perforations 210. In some embodiments, the cover element 230 may be formed as a film, such as an elastomeric film, comprising thermoplastic polyurethane (TPU), polypropylene, polyethylene, high-density polyethylene, polybutylene terephthalate (PBT), silicone, SURLYN® resin, nylon, rubber (such as nitrile rubber, styrene-butadiene rubber, thermoplastic elastomers, or other rubber materials), or a film of another polymer or resin material suitable for use as a hitting surface in a ball striking area. In some embodiments, a thin shrink-film material may be used as the cover element 230 to cover the perforations 210. In some embodiments, the cover element 230 may include a plastic shell or another shell comprising acrylonitrile butadiene styrene (ABS), nylon, polycarbonate, polyethylene terephthalate (PET), polyurethane, or a composite material that includes an epoxy, polyurethane, or thermoplastic resin matrix.

A thin cover element 230 may deform when impacted by a ball, such that an outline of the perforations 210 may become visible or the cover element 230 may become damaged. Although filler material 220 may optionally be omitted when a cover element 230 is included, in some embodiments, filler material 220 positioned in the perforations 210 under the cover element 230 may reduce deformation of the cover element 230. In some embodiments, using relatively smaller perforations 210 may help reduce deformation of a cover element 230. A person of ordinary skill in the art will recognize considerations of material strength, thickness, perforation size, quantity of perforations, and desired overall durability to meet the needs of a particular application, and to design ball bats according to embodiments of the present technology.

Ball bats according to embodiments of the present technology may be made with composite laminate material. For example, FIG. 3A illustrates a cross-sectional view of a stack of composite laminate layers 300 with perforations 310 a, 310 b, 310 c, and 310 d, the stack forming at least part of the barrel wall 196, according to embodiments of the present technology. For simplicity in illustration, only some layers 300 are labeled in the figures. The cross-sectional view in FIG. 3A may be a view of section “A” in FIG. 1B. FIG. 3B illustrates a face-on cross-sectional view of a section of a ball bat, such as at least a portion of the section represented in FIG. 3A, with perforations 310. In some embodiments, a barrel wall 196 may include two or more layers 300 of composite laminate material formed concentrically around the interior cavity 197. A composite laminate bat according to embodiments of the present technology may be manufactured according to composite manufacturing techniques such as resin-transfer molding (RTM) or by “laying up” the layers 300 around a mandrel or bladder mold before curing.

In some embodiments, one or more layers 300 of the composite laminate stack may have one or more perforations 310 (such as 310 a, 310 b, 310 c, and 310 d), which may be suitably sized or shaped holes in an individual layer 300 or in two or more layers 300. For example, in some embodiments, perforations 310 a, 310 d may be formed in middle or interior layers 300, while other perforations 310 b, 310 c may be formed in layers 300 that are closer to the interior cavity 197 or to an outward layer 320 than to a middle or interior layer 300. In some embodiments, a composite laminate layer 300 with one or more perforations may be positioned between other layers 300 of composite laminate material in the barrel wall, so that the one or more perforations 310 are positioned radially between the other layers 300 of composite laminate material in the barrel wall. In various embodiments, the other layers 300 surrounding the layer 300 that includes perforations may or may not include perforations. In some embodiments, portions of the other layers 300 adjacent to the perforations 310 may be continuous and not perforated, such that the perforations 310 are positioned radially between composite laminate material in the other layers 300. Various suitable numbers of perforations 310 in various patterns distributed among the various layers 300, suitable for reducing weight while maintaining compliance with performance regulations, may be used in various embodiments of the present technology.

The perforations 310 may be formed in individual layers during the composite layup process, such as by punching holes, cutting, or otherwise removing material from the composite layers 300. For example, a punch press or die may be used. In production, a mandrel or inflatable bladder mold positioned in the interior cavity 197 may press outwardly on the layers 300 while a mold around an outermost layer (such as the outward layer 320) presses inwardly on the layers 300. Compressing the layers 300 together during the layup and curing processes causes neighboring concentric layers 300 to deform (such as pucker) into the perforations 310 to fill the void in the perforations 310, as illustrated in FIGS. 3A and 3B. Accordingly, embodiments of the present technology include methods of making a ball bat by perforating or otherwise providing holes in layers of composite laminate material, laying up the layers on a mandrel or inflatable bladder mold, positioning the layers and mandrel or bladder mold in an outer mold, compressing the layers together, and curing the layers.

In some embodiments, resin from neighboring composite laminate layers may flow into the perforations 310. In some embodiments, the perforations 310 may be small enough to prevent fibers in neighboring composite laminate layers 300 from entering the perforations 310, while in other embodiments, the perforations 310 may be large enough to allow fibers from neighboring composite laminate layers 300 to migrate into the perforations 310. Whether the perforations 310 allow or prevent fibers in neighboring layers to enter the perforations 310 will affect the resulting strength of the barrel wall 196 or the overall ball bat.

Fibers migrating into the perforations may strengthen the resin within the perforation while weakening the strength of the neighboring composite layers from which the fibers migrate. In some embodiments, fiber migration from the neighboring composite layers into the perforations may reduce the strength difference between the perforations and the surrounding structure. Because large differences in strength and stiffness between areas in a bat wall can cause a stress concentration that can lead to failures in the stress concentration area, fiber migration may reduce the risk of forming a stress concentration area near the perforations. Accordingly, the size of the perforations 310 and the types of resin and fiber materials may be selected to determine overall strength and performance characteristics of a finished bat.

In some embodiments, if the resin matrix and fiber structure are sufficiently strong and stiff, perforations may be sized such that fibers do not enter the perforations, however, if the resin matrix and fiber materials are selected such that they are less strong or stiff, fiber migration into the perforations may improve the overall strength of the bat by reducing stress concentration factors.

In some embodiments in which the matrix material itself is relatively weak or brittle on its own (without the support of a fiber structure), such as matrices formed with vinyl ester epoxy resin, polycarbonate, acrylic, phenolic matrix materials or other relatively brittle matrix materials, perforations may be sized to allow fiber migration to improve the overall strength of the finished bat. In such embodiments, fibers with relatively higher toughness and tenacity (such as fiberglass, s-glass, polyethylene such as Dyneema® or Spectra®, olefin fibers such as Innegra®, or aramid fibers such as Kevlar®) may be used as opposed to more brittle fibers (such as carbon, boron, or basalt) to further change the overall strength of the bat. Tougher resins such as epoxy resins, polyurethane, nylon, polyether ether ketone, polysulfone, or other relatively tougher resins may be used be used in embodiments in which fibers do not enter the perforations. Various combinations of matrix materials and fibers may be used in various embodiments, with or without migration of the fibers into the perforations, to tailor the overall strength of the bat.

The perforations 310 reduce the overall weight of the ball bat, while allowing the bat to maintain sufficient structural rigidity and durability, and to comply with performance regulations such as BBCOR.

FIG. 4A illustrates a cross-sectional view of a stack of composite laminate layers 300 with perforations 400 a, 400 b, the stack forming at least part of the barrel wall 196, according to embodiments of the present technology. The cross-sectional view in FIG. 4A may be a view of section “A” in FIG. 1B. FIG. 4B illustrates a face-on, cross-sectional view of a section of a ball bat, such as at least a portion of the section represented in FIG. 4A, with perforations 400 (such as perforations 400 a, 400 b).

In some embodiments, as shown in FIG. 4A, one or more perforations 400 a may pass through all or substantially all the layers 300 (through thickness T2, in a manner similar to the perforations 210 described above with regard to FIGS. 2A-2C). In some embodiments, one or more perforations 400 b may pass through only some of the layers 300. Through-perforations 400 a and partial-perforations 400 b may be formed by laying up perforated layers 300, aligning the perforations in each layer 300, then curing the assembly, or they may be formed by removing material from a cured or uncured stack of layers 300 (such as by cutting, drilling, or another suitable method of removing material).

In some embodiments, to maintain a smooth outer surface of the ball bat, a partial perforation 400 b may be positioned to open towards the interior cavity 197 rather than toward an outward layer 410. In some embodiments, the partial perforation 400 b may be positioned to open away from the interior cavity 197 (for example, as an opening in outward layer 410). Perforations may be arranged or distributed in any suitable pattern along the longitudinal axis of the ball bat or around the circumference of the wall 196 that provides reduced weight while allowing the bat to maintain compliance with performance regulations, such as the patterns described and illustrated with regard to FIGS. 2A and 2B, or other suitable patterns.

In some embodiments, as shown in FIG. 4B, the perforations 400 (including through-perforations or partial-perforations) may be arranged or distributed in any suitable pattern around the circumference of the wall 196 or along the longitudinal axis of the ball bat that provides reduced weight while allowing the bat to maintain compliance with performance regulations. In some embodiments, the distribution of types and sizes of perforations may be uniform around the wall 196 or, in other embodiments, the types and sizes of perforations may be mixed around the wall 196.

In some embodiments, the perforations 400 may be partially or completely filled (or covered) with one or more filler materials 420, 430. The filler materials 420, 430 may be similar to or the same as the filler material 220 described above with regard to FIG. 2C. In some embodiments, wood (such as balsa wood), SURLYN® resin material, or other materials may be positioned in the perforations. In some embodiments, the filler material (220, 420, 430) may be formed as a solid hollow tube (like a straw) or a solid shaft of material, or another form suitable for filling the perforations. In some embodiments, the filler materials may be positioned in the perforations 400 before curing the bat to prevent matrix material or fiber material from filling the perforations 400 before or during the curing process. As described in additional detail above, the filler materials may be selected to have lower density than the remaining material in the wall 196, so that the final bat assembly has reduced weight.

In some embodiments, the layers 300 may be perforated together, or they may be perforated separately and brought together so the perforations in each layer 300 are aligned to form a larger perforation 400, which may be described as an aggregate hole formed by the plurality of the generally aligned perforations, and which may extend through part or all of the barrel wall 196 in various embodiments. Accordingly, embodiments of the present technology include ball bats and methods of making ball bats by perforating or otherwise providing holes in layers of composite laminate material, and laying up the layers so that the perforations are generally aligned, then curing the layers in a suitable curing process to form at least part of a ball bat.

In some embodiments, as shown in FIG. 4B, a cover element 230 may be positioned over one or more of the perforations 400, in a radially outward direction from the perforations. The cover element 230 is described above in additional detail with regard to FIG. 2C.

Embodiments of the present technology provide reduced bat weight or reduced swing weight while remaining compliant with performance requirements or limitations, such as BBCOR requirements or limitations. For example, weight reductions of ten percent or more (relative to bats without perforations) may be achieved with the present technology. In some embodiments, ball bats according to embodiments of the present technology may be single-wall configurations, double-wall configurations, or other configurations, and the perforations may be positioned in one or more walls of a multiple-wall bat. Preferably, however, the perforations are positioned in an outermost wall of a multiple-wall bat, or in the wall of a single-wall bat (as illustrated in the Figures). Perforations may be arranged in any suitable pattern and in any suitable quantity sufficient to decrease swing weight and maintain compliance with performance and strength requirements or limitations. Perforations may be positioned within the striking area. In some embodiments, perforations may be positioned only within the straight section 160, although in other embodiments perforations may be positioned in the taper portion 130. In general, if filler materials or cover elements are used to fill or cover the perforations, the filler material is preferably different from the material forming the remainder of the barrel wall. For example, filler material or cover-element material may have lower density and lower overall weight than the remainder of the material forming the barrel to maintain the reduction in overall weight achieved by removing material to form the perforations.

From the foregoing, it will be appreciated that specific embodiments of the disclosed technology have been described for purposes of illustration, but that various modifications may be made without deviating from the technology, and elements of certain embodiments may be interchanged with those of other embodiments, and that some embodiments may omit some elements.

Further, while advantages associated with certain embodiments of the disclosed technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology may encompass other embodiments not expressly shown or described herein, and the invention is not limited except as by the appended claims. 

1. A ball bat comprising a handle, and a barrel attached to or continuous with the handle along a longitudinal axis of the bat, the barrel comprising a barrel wall formed with a plurality of layers of composite laminate material and surrounding a hollow interior cavity of the bat, wherein a plurality of perforations extend through the barrel wall, wherein the perforations are distributed around the barrel wall and positioned within a ball striking area of the bat, and wherein the ball bat further comprises: (a) a filler material positioned in one or more of the perforations to form a generally flush surface between the filler material and an outer surface of the barrel wall; or (b) a cover element positioned over one or more of the perforations.
 2. The ball bat of claim 1, wherein the ball bat comprises the filler material, the filler material having a density less than a density of a material forming the barrel wall, and wherein the filler material comprises wood, epoxy, resin, foam, rubber, or plastic.
 3. The ball bat of claim 1, wherein the ball bat comprises the filler material and the cover element.
 4. The ball bat of claim 1 wherein the handle includes a plurality of layers of composite laminate material.
 5. The ball bat of claim 1 wherein the handle includes a metal alloy.
 6. (canceled)
 7. (canceled)
 8. The ball bat of claim 1 wherein one or more of the perforations has a width between 0.040 inches and 0.125 inches.
 9. The ball bat of claim 1 wherein the perforations are arranged in offset rows.
 10. A ball bat comprising: a handle; and a barrel attached to or continuous with the handle along a longitudinal axis of the bat, the barrel comprising a barrel wall; wherein the barrel wall includes a plurality of layers of composite laminate material, wherein at least one of the layers of composite laminate material is positioned between other layers of composite laminate material and has one or more perforations.
 11. The ball bat of claim 10 wherein the one or more perforations are positioned radially between composite laminate material in the other layers of composite laminate material in the barrel wall.
 12. The ball bat of claim 11 wherein at least one of the other layers of composite laminate material is deformed into the one or more perforations.
 13. The ball bat of claim 10, comprising a plurality of perforations, wherein the plurality of perforations are generally aligned and form an aggregate hole extending through at least part of the barrel wall.
 14. The ball bat of claim 13, further comprising a cover element positioned over the aggregate hole in a radially outward direction from the aggregate hole.
 15. The ball bat of claim 13 wherein the aggregate hole opens into an interior cavity of the ball bat.
 16. The ball bat of claim 13, further comprising a filler material positioned in the aggregate hole, wherein the filler material is different from, and has a lower density than, material forming the layers of composite laminate material.
 17. The ball bat of claim 16 wherein the filler material is formed as a shaft or a hollow tube.
 18. A ball bat comprising: a handle formed with a metal material; and a barrel attached to or continuous with the handle along a longitudinal axis of the bat, the barrel comprising a barrel wall formed with a metal material, the barrel wall surrounding a hollow interior cavity of the ball bat; wherein the barrel wall includes a plurality of perforations extending at least partially through a thickness of the metal material and distributed circumferentially around the barrel wall in a striking area of the bat.
 19. The ball bat of claim 18, further comprising a means for filling or covering the perforations to form a generally flush outer surface of the bat.
 20. The ball bat of claim 18 wherein the metal material in the barrel has a first density, the means for filling or covering the perforations has a second density, and wherein the second density is less than the first density. 